There’s been a lot of talk about custom post types, and I know many people are looking forward to it. Unfortunately, I think some (perhaps many) of those people are going to be disappointed. Custom Post Types might not be what you think they are.

I blame the naming, really. “Custom Post Types” makes the implication that these are “Posts”. They’re not. “Post Type” is really referring to the internal structure of WordPress. See, all the main content in WordPress is stored in a table called “wp_posts”. It has a post_type column, and until now, that column has had two main values in it: “post” and “page”. And there’s the big secret:

“Custom Post Types” are really Pages.

Sorta.

For a long time in the early days of WordPress, it just had Posts. But hey, no big deal, because it was just running a big Blog anyway, right? The Posts appeared on the Blog page (and in the Feed) in reverse chronological order. Each Post could appear on its own URL, using the Permalink structure.

Pages came along and changed that.

Pages don’t appear on the Blog. Or in the Feed.

Pages don’t even really have dates and times on them that usually get displayed.

Pages have their own URL at the root of the website, outside the Permalink rules.

Pages even have hierarchy in their URLs, if they want.

Pages, however, do live in the wp_posts table. So post_type exists to handle that. When WordPress is building the Blog, it looks for post_type = “post”.

Bring on the “Custom”.

Now we have these Custom Post Types. Or rather, custom post_types. Instead of “page” or “post”, we can have “custom”. Or “fred”. Whatever we like.

But how do these new post types get displayed? What do their URLs look like?

Well, these are custom, and they can be customized. You can give them their own space on the website. So if I want them to live at /custom/page-name, then I can. If I want them to have hierarchy, then I can do so. Justin Tadlock explains how they can be made to do this quite well.

But they are still not Posts.
They do not show up on the Blog.
They do not appear in the Feed.

This is a matter of definitions, really. See, the Blog is a reverse chronological order of the Posts. That it what it is defined to be. The Feed is basically the same thing, in feed form.

So all of you thinking of a custom “Podcast” post type, you’re in for a disappointment.

So what’s the big deal?

Well, all that said, custom types can have their own systems of doing things. They are custom, and as such, they are customizable.

If, for example, you wanted to have them appear on their own “blog” area, or in their own “feed”, then sure, that’s entirely doable. You can make a function to produce your custom feed. You can then call “add_feed” to add your feed. You can create single-type.php templates in your theme that will be used for your custom type. You could even make a “blog” out of your custom type.

And doing it the other way is possible too. You can adjust the “Blog” to show your type. You could change the “Feed” to show your type as well.

But these things are NOT the default way of doing things. There’s no code in there to do that, and there’s very likely not going to be. If you want your type in the Blog, in the Feed, then you have to do it yourself. The URL is NOT easy to customize and play around with. The rewrite system is unforgiving, and you have to stick within a set of rules for things to work well.

However, should you? Let’s say you make a “Podcast” custom type. You can go to the effort of putting them in the feeds and making them show special on the blog… but you could already do that with a “podcast” category. And it’s much easier to do a category and customize categories than custom types will ever be.

Something like 80% of the uses I’ve seen for “custom types” would be better served by making normal posts and using some existing method to separate them or to otherwise mark them as special.

So what are they good for?

What if you could install a forum on your site? bbPress is pretty good. But it could get all complicated to set up and such. Well, plugins are pretty easy. But all those forum posts have to go somewhere…

Custom Post Types is a way for plugins to define types of content for themselves.

A bbPress forum could store every post in the forum as its own custom post type quite easily.Or a wiki plugin could store each of its own pages as a custom post type. Things like that.

See, they’d get their own URL handling automatically, and they wouldn’t need weird database handling tricks.. It makes things much simpler and easier for those plugins to do their thing when they have the backend support for it in the core.

Some of you are thinking “Okay, so plugin authors can make better use of them. I won’t have to write a lick of code, I’ll just install a plugin that makes my type and handles the stuff for me.” And yeah, you can do that.

But then you’re wedded to that plugin. WordPress doesn’t know about your custom posts. If you remove the plugin, your custom posts are still there, but now they’re completely invisible. Can’t be pulled up, seen in the admin, the URLs all stop working…

Wrap it up, son…

Using custom post types right now is, for most people, a bad idea. Only specialized usages really exist for them… for now.

For the long term, WordPress will probably use them a lot more extensively. And plugins can make great use of them for all sorts of things. But you, as a user, probably don’t need to be messing with them. Not if you’re just creating a website or writing a blog. Not right now. Wait for the plugin and core development to catch up to the potential. Using them early leaves you open for a world of confusion and grief.

Nasty, eh? It’s a mess of if/else statements. It handles cases where the user is logged in or not, where the comments are open or closed, whether registration is required, etc. It’s confusing, difficult to modify, poor for CSS referencing…

Here’s what I replaced all that code with:

<?php comment_form(); ?>

Now then, that’s much better, isn’t it?

The comment_form function is new to 3.0. Basically, it standardizes the comments form. It makes it wonderful for us plugin authors, since now we can easily modify the comments form with various hooks and things. I’ve already modified Simple Facebook Connect and Simple Twitter Connect to support this new approach; if you’re using a theme with this, then the user won’t have to modify it to have their buttons appear on the comments form.

Customizing

Since theme authors love to customize things, the comments form is also extremely customizable. Doing it, however, can be slightly confusing.

Inside the comments_form function, we find some useful hooks to let us change things around.

The first hook is comment_form_default_fields. This lets us modify the three main fields: author, email, and website. It’s a filter, so we can change things as they pass through it. The fields are stored in an array which contains the html that is output. So it looks sorta like this:

All the various pieces of html that are displayed as part of the comment form section are defined here. So those can be modified as you see fit. However, unlike the fields, adding new bits here won’t help us at all. The fields get looped through for displaying them, these are just settings that get used at various times.

But filters are not the only way to modify these. The comment_form function actually can take an array of arguments as the first parameter, and those arguments will modify the form. So if we wanted a simple change, like to change the wording of “Leave a Reply”, then we could do this:

<?php comment_form(array('title_reply'=>'Leave a Reply, Stupid')); ?>

This gives us a simple and easy way to make changes without all the trouble of filters. Nevertheless, those filters can be very useful for more complex operations.

But wait, there’s more!

As the comments form is being created, there’s a ton of action hooks being called, at every stage. So if you want to insert something into the form itself, there’s easy ways to do it.

A quick list of the action hooks. Most of them are self-explanatory.

comment_form_before

comment_form_must_log_in_after

comment_form_top

comment_form_logged_in_after

comment_notes_before

comment_form_before_fields

comment_form_field_{$name} (a filter on each and every field, where {$name} is the key name of the field in the array)

comment_form_after_fields

comment_form_field_comment (a filter on the “comment_field” default setting, which contains the textarea for the comment)

comment_form (action hook after the textarea, for backward compatibility mainly)

comment_form_after

comment_form_comments_closed

CSS and other extras

Let’s not forget styling. All parts of the comments form have nice classes and id’s and such. Take a look at the resulting HTML source and you’ll find all the styling capabilities you like. Also, everything is properly semantic, using label tags and aria-required and so forth. All the text is run through the translation system for core translations.

So theme authors should start modifying their themes to use this instead of the existing big-ugly-comment-form code. Your users will thank you for it. Plugin authors will thank you for it. And really, it’s about time we made WordPress themes more about design and less about the nuts and bolts of the programming, no?